My clotting speed varies a lot, and now all my blood tests over the past 2 years show an excess of red blood cells, ie my blood is thicker at those times - no idea why and my docs don't really have any answers, they just change the subject.
It wasn't even noted down when I bled all over the floor after a nurse very carefully removed a cannula from my hand.
I discovered last year that one of my uncles has the same clotting issue, in his case it's marked on his notes so his gets checked before operations!